Dental deflasking mechanism



Feb. 12, w46. J EHNER 2,394,921

DENTAL DEF'LASKING MECHANISM Filed July 8, 1944 2` Sheets-Sheet l Feb. 12, 1946. J. LEHNER 2,394,921

DENTAL DEFLASKING MECHANISM Filed July 8, 1944 2 Sheets-Sheet 2 y k/O 9 y j@ 39 ig---n-w-n--a---Jw Zig --j /l l I f 2? 24 2Q IN VEN TOR.

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Patentedreb. 12, 1946 UNITED STATE DENTAL DEFLASKING MECHANISM John Lehner, Brentwood, Pa.

6 Claims.

The present invention relates to the manufacture of oral replacements, and more particularly to the mechanical removal of the hardened mass of dental investment from the flasks in which the replacements have been vulcanized.

After the replacement, 'which is embedded in investment material within the ask, has been vulcanized, under the present practice much diiiiculty is incurred in removing the hardened investment from the flask. The method for dislodging the mass of investment from the ask now in general use is to remove the investment material from the liask by cutting, scraping, and the use of prying tools and hammer, but the operation is time-consuming and may result in damage to the embedded oral replacement.

The principal object which I have in view is the provision of means and a method by which the mass of hardened investment material may lbe forcibly ejected from the flask Without disintegrating the mass or endangering the product embedded therein.

During vulcanization a two-pan', metal flask is commonly used, and in the present practice one of the dicult steps in removing the mass of investment material from the ask is the separation of the ask parts which is commonly done with a prying tool.

In the case of my present invention the flask parts are separated mechanically simultaneously with the loosening of the investment material from one flask part, and subsequently the entire mass is mechanically released from the other flask part.

I have invented a new and improved mechanism for dislodging the investment material from the iiasks which may also be used as a denture press for pressing the flask parts together in the usual manner. I thus combine in one mechanism two important functions.

Another feature of my present invention is an improved two-part metal mold structure fo-r use in connection with my deasking mechanism to facilitate the dislodgment of the mass of investment material.

Other novel features of construction and arrangement of parts will appear from` the following specification.

In the accompanying drawings, wherein I illustrate a practical embodiment of the principles of my invention:

Fig. 1 is a front elevation showing the ejection mechanism with the two-part mold, containing the investmentmaterial and the vulcanized re- Application July s, 1944, serial No. 544,099

placement, suspended in position for the ejection of the material from the upper mold part.

Fig. 2 is an incomplete end elevation of the same.'

Fig. 3 is also an incomplete end elevation which illustrates the secondstep of ejection-that of ejecting the mass of investment material from the lower mold part.

Fig. 4 is a detail view, partially in section showing the arrangement of the mold-suspension links, the screw shaft, and the impact disk and striking rod.

Fig. 5 is a side elevation view of the mass of hardened investment after it has been ejected from both mold parts.

Fig. 6 is a top plan view of the upper mold part, the same being shown with the closure lid removed.

Fig. '7 is a side elevation of the two-part mold assembled as it appears when it contains the investmentmaterial and pattern.

Fig. 8 is an end elevation of the assembled mold.

Figs. 9 and 10 are, respectively, a plan view and a sectional view along the line Ill-I0 in Fig. 9, showing one of the mold closure lids which are employed when pressure is to be applied to the lled mold.

Figs. 11 and 12 are, respectively, similar views of the pressure lid which is substituted in turn forthe upper and lower lids during the steps of the ejection operation, Fig. 12 being a section taken along the line I 2-I 2 in Fig. 1 1.

Referring first to Figs. 1 to 4 inclusive of the drawings, I0 indicates the deasking mechanism, the frame of which is shown composed of a iiat base II, and an elevated platform I2 supported from the base II by means of the posts I3. I 4 indicates a vertically disposed eXteriorly threaded tubular shaft which extends down through a corresponding threaded bore in the platform I2 and a tubular boss I5 extending up from the platform at its center. By rotating the shaft I4 in the proper direction it may be screwed up or down relative to the platform. The upper end of the shaft is provided with a diametrically disposed handle I6.

Extending down through the bore ofthe tubular shaft I4 is the impact rod I1 whose lower end is provided with a pressure disk I8. The upper end of the rod I'I extends some distance beyond the upper end of the shaft I4 and is provided with a cross pin or abutment I9, and 2li/indicates a helical spring coiled about the rod Il with its upper end bearing against the abutment and its lower end bearing against the upper end of the shaft I4.

The function of the spring 20 is to normally retain the rod I1 in its elevated position with the disk I8 in contact with the lower end of the shaft I4, and also to automatically return the rod to its normal position after a blow, as of a hammer, has been struck on the upper end of the rod to force the disk downwardly and away from the lower end of the shaft I 4.

At the center of the front and rear edges of the platform I2 are attached the hinges 2| by means of which the swing hook links 22 are hingedly connected` at their upper ends to the platform. These links are preferably formed of iiat metal and have their lower, free extremities provided with inwardly hooked flanges 23, which' are arranged to enter and engage the longitudinally slotted recesses 24 in the exterior walls of the mold parts 25 and 2'6.

In Figs. l and 2` the hook links 22 are supporting the assembled two-part mold 25--26 by their engagement with the recesses 24 of the upper mold part 25, -while inwFig. 3 the lower mold part 26 is shown suspended by the links in an inverted position with the mass 21 of investment material partially protruding downwardly therefrom, the mass being partially exposed from view by the previous removal of the mold Dart 25.

Referring now to Figs. 6 to 10 inclusive of the drawings, the upper and lower mold parts 25 and 26 are substantially of the same contour except that the lower mold part is inverted, both enlarging interiorly toward what are their mating edges when assembled. This is to facilitate the ejection of the hardened investment material from the mold after the oral replacement has been vulcanized.

At their mating ends the mold parts are open to their full interior dimensions but at their other ends the top and bottom ends, respectively, of the upper and lower mold parts a depressed interior shoulder or ledge 28 is provided.

In preparing the flask and its contents for the production of the oral replacement, the cover lids 29 are placed on the outer ends of the two mold parts, said lids being of proper perimetral dimensions to t on the perimetral edge of the mold parts, the body of the lids being of suiclently less dimensions to t down within the ledges 28 as indicated at 30, so that when the investment material has hardened in the assembled mold a depression is formed on the upper and lower surfaces of the hardened mass. When the hardened material is to be ejected from the mold a false or pressure lid 3l is substituted for the cover lid, such pressure lid being of such dimensions to fit down within the ledge 28 and into the depression formed in the material by the body 39 of the cover lid 29.

When my improved deiiask mechanism is to be employed as a dental press, prior to the vulcanization or polymerization of the material of the oral replacement, the assembled mold with the cover lids 29 in position and the interior of the mold filled with plastic investment materal in which the mold is embedded, is placed on the base Il and centered under the pressure disk I8. Then the tubular shaft I 4 is screwed down forcing the disk I8 against the cover lid 29 of the upper mold part 25, thus pressing the ask part snugly together.

It is commonly recognized that the vulcanizing or polymerizing operation not only renders the investment material exceedingly hard but also causes it to adhere tightly to the surface of the metal mold parts and that much diiliculty is experienced and labor required to eject the investment material from the mold parts and permit the opening up of the mass to remove the oral replacement which has been produced.

In the use of my mechanism for deasking the upper and lower lids 29 are first pried of the end of the mold parts and the smaller pressure lid 3| is substituted on the upper mold part 25.

The mold assembly is then, as illustrated in Figs. 1 and 2, suspended in the mechanism I0, beneath the platform I2, by engaging the hooked extremities 23 of the links 22 in the recesses 24 in the walls of the mold part 25.

The shaft I4 is then screwed down to force the false lid 3| down through the interior of the mold part 25 to push the investment material ahead of it and thus separate the mold parts, the lower mold part remaining attached to its hardened mass of investment material. However difculty is usually experienced in this stripping of the upper mold part from the mass of hardened investment material owing to the strong adhesion between the investment and the metal.

In such case a smart hammer blow is fstruck on the protruding upper end of the impact rod I1, forcibly driving the pressure disk I8 againstthe false lid 3l and rupturing the attachment between the investment material and the metal.

By this operation the hardened investment material is separated from the upper mold part 25 but the entire hardened mass remains firmly anchored in the lower mold part in which it is partially contained.

Then, as illustrated in Fig. 3, the lower mold part is inverted and suspended by the hook links 22 and the false lid is placed on top of the investment material in the mold part. The pressure plate I8 is then forced down by rotation of the shaft I4 and hammer blows are intermittently struck as needed on the upper end of the rod I1 until the mass of investment material is ejected from the mold part 26. The investment mass may then be opened and the oral replacement removed for final nishing.

It is evident from the foregoing description that by means of my invention the operation of deflasking, now a tedious and dimcult task, may be accomplished quickly and without danger of injury to the product.

I claim:

l. Apparatus, 'for deflasking the hardened contents of a dental flask member, which comprises means for suspending the flask memberxfrom above with its cover lid removed, ejecting means for applying a downwardly eiective force to the hardened contents of the flask member to discharge the same, and means for transmitting to the ejecting means a sudden impact to assist in rupturing adhesions between the contents and the walls of the ilask member.

2. Apparatus, for deflasking the hardened contents of a dental ask member, which comprises an elevated support, means depending from said support to suspend a dental flask member with its cover lid removed, screw means carried by said support for applying a progressive force to the contents of the flask member to eject the same, and means associated with the screw means for transmitting a sudden downwardly efective impact to the contents to rupture adhesions of the contents to the walls of the iiask member.

3. Apparatus, for delasking the hardened contents of a dental ask, which comprises an elevated support, means for suspending a. dental flask from said support, a tubular screw shaft extending down through said support and having threaded engagement therewith whereby said shaft may be moved axially by rotation thereof, a rod extending downwardly through the bore of the shaft, and a contact disk attached to the lower end of the rod and arranged to be forced downwardly in contact with' the contents of the flask by rotation of the shaft to force the contents through the lower end of the ask, the upper end of the rod protruding from the shaft to receive a blow as of a hammer and impart a sudden impact on the contents to rupture adhesions to the walls of the flask.

4. Apparatus for deflasking the hardened contents of a dental flask, which comprises an elevated support, means for suspending a dental l' flask from said support, a tubular screw shaft extending down through said support and having threaded engagement therewith whereby said shaft may be moved axially by rotation thereof, a rod extending downwardly through the bore of the shaft, a contact disk attached to the lower end of the rod and arranged to be forced downwardly in contact with' the contents of the flask by rotation of the shaft to force the contents through the lower end of the flask, the upper end of the rod protruding from the shaft to receive a blow as of a hammer and impart a sudden impact on the contents to rupture adh'esions to the walls of the flask, and means to return the rod, after an impact, to position the disk against the lower end of the tubular shaft.

5. Apparatus, for deflasking the hardened contents of an open ended dental flask, which cornprises an elevated support having a threaded bore therethrough, depending links having their upper ends hinged to the support and their lower ends provided with means for engaging the outer wall of the flask to suspend the latter and a screw shaft threadedly engaged in said bore and extending therethrough, said shaft arranged to be moved axially by rotating the shaft, the lower end of the shaft when the latter is moved downwardly exerting a force upon the contents of the flask to impel the same through the lower end of the ask.

6. Apparatus, for deasking the hardened contents of an open ended dental flask, comprising an elevated support having a threaded bore therethrough, depending links having their upper ends hinged to the support and their lower ends provided with' means for engaging the outer wall of the flask to suspend the latter, a tubular screw shaft threadedly engaged in said bore and extending therethrough, said shaft arranged to be moved axially by rotating the shaft, an impact rod extending through said shaft, an impact disk attached to the lower end of the rod which disk is forced down on the contents of the flask when the shaft is moved downwardly, and resilient means normally holding the rod elevated and the disk in contact with the lower end of the shaft but permitting a sharp impulse to be imparted to the contents of the flask when a blow as by a hammer is struck on the upper end of the rod to rupture adhesions between the contents and the walls of the flask.

JOHN LEHNER. 

